Athanor by arbastro
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How to show terminal carbons and atom numbers

Choose View › Show terminal carbons and View › Show atom numbers. For one structure, select it and switch Terminal C and Atom numbers on under Display in Properties.

For the whole page

  1. Choose Main menu › View › Show terminal carbons. Chain ends are written as H₃C.

  2. Choose Main menu › View › Show atom numbers. Every atom gets its number.

    Butanoic acid with H3C written out and atoms numbered 1 to 6.Butanoic acid with H3C written out and atoms numbered 1 to 6.

For one structure

Select the structure and open Display in Properties. Each switch applies to that structure only:

Display in Properties: R/S labels, Terminal C, Atom numbers and Aromatic.Display in Properties: R/S labels, Terminal C, Atom numbers and Aromatic.

Switch Shows
R/S labels The CIP label on each stereocenter. See stereochemistry labels
Terminal C CH₃ at chain ends
Atom numbers A number on every atom
Aromatic Kekule or Circle
Atoms, bonds and ringsHow to show R and S, E and Z labelsTurn on View › Show stereochemistry. Each stereocenter gets R or S and each stereo double bond E or Z, worked out from the CIP priority rules and updated as you draw.

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Last updated Nov 12, 2026